Production of electronic packages involves picking a semiconductor chip or die from a tray or wafer and placing it on a substrate on which it is to be bonded. The bonding between the die and the substrate, which can be glass, printed circuit board or ceramic, is achieved using solder or adhesive while applying heat and force. The solder or adhesive is deformed under heat and force and electrical connection is established between the die and the substrate.
The apparatus used to apply heat and force is referred to as a bond head. FIG. 1 is a side view of a conventional die bonding apparatus 100. The bonding apparatus 100 includes a bond head 103 comprising a bonding tool 104. The bonding tool 104 holds a die 106 and is driven directly by a pneumatic cylinder 102 towards a substrate positioned on top of a base 108 of the bonding apparatus 100. Motion of the bond head 104 is guided by a linear guide 110 which is mounted onto a stand 112, and which in turn rests on the base 108. Upon contact, the die 106 held by the bonding tool 104 is bonded onto the substrate using force exerted from the pneumatic cylinder 102 and heat produced from the bonding tool 104 and/or base 108.
Since the die may be of various sizes and configurations, the force that has to be applied on the die typically depends on the number of electrical connections between the die and substrate. The force applied will have to be greater if there are more electrical connections. The aforesaid prior art utilizes an electromagnetic actuator or pneumatic cylinder 102 to apply a bonding force onto the die. The force required typically varies from 5 gf to about 50 kgf.
To increase throughput, some bonding machines provide multiple bonding heads in order to bond more than one die simultaneously. As the number of electrical connections between the die and substrate increases, the force that has to be provided by the bond head becomes larger, and bigger electromagnetic actuators or pneumatic cylinders have to be used. These requirements demand that a gap between separate bond heads should be at least 40-50 mm. Bonding of multiple dice on the substrate with small inter-spacing simultaneously is thus not possible. This limits the throughput when, for instance, there is a need to bond multiple dice simultaneously onto a small LCD panel.